@mixin flexCenter {
    display: flex;
    align-items: center
}
$colors:(
    bg:#00bcd4,
    text-color:#333,
    primary:#00bcd4,
    nav-head:#fff,
);
@function color($key) {
    @if map-has-key($colors, $key) {
        @return map-get($colors, $key);
    }

    @warn "Unknown `#{$key}` in $colors.";

    @return null;
}